Embodiments of the present specification relate to thermal interfaces, and more particularly to thermal interface devices.
Electronic devices often produce heat during operation that needs to be dissipated away from the electronic devices to prevent over heating of one or more components of the electronic devices. As will be appreciated, overheating of the components of the electronic devices may result in reduced reliability and/or failure of the electronic devices. Heat sinks are often used for dissipating heat away from the electronic devices. A heat sink is a passive component that is used to lower a temperature of an electronic device by dissipating heat away from the electronic device into the surrounding environment. In order for the heat sink to operate efficiently, the heat from the electronic device must be transferred to the heat sink over a thermal connection.
Typically, the electronic device includes a plurality of electronic components attached to a printed circuit board (PCB). One or more of these electronic components generate heat and may be referred to as “heat sources.” Heat from these multiple components is transferred to one or more heat sinks using thermal connections. Each component on the PCB is disposed at a particular distance from the heat sink (tolerance) and the heat must be effectively transferred across the tolerance from the component to the heat sink. Accordingly, the tolerance is often filled with a thermal connector, such as a compliant heat spreader and/or thermal interface material. The thermal connector serves to provide an efficient thermal connection by filling up micro-voids present on a surface of a heat source and a surface of the heat sink. In addition, the thermal connector serves a mechanical function by providing a compliant mechanical connection between the heat source and the heat sink. It may be noted that typically the heat source and the heat sink have different coefficients of thermal expansion.
Additionally, when a single heat sink is used for the multiple electronic components, the thermal connectors are required to accommodate different tolerances pertaining to the multiple electronic components. It is desirable to employ the thermal connectors that are compressible and expandable to meet the demands of the different tolerances of the multiple electronic components. In some instances thermal pastes, thermal greases and thermally conductive pads may be used as the thermal connectors. However, typically, these thermal connectors have thermal conductivities as low as about 3 watts per meter Kelvin (W/mK). Although, thermally conductive pads may have thermal conductivities as high as about 17 W/mK, however, these thermally conductive pads can only be compressed between about 10% to about 20% of their original size. This limitation on the amount of compression possible for the thermally conductive pads limits a size of a gap between the electronic component and the heat sink. Further, this limitation on the amount of possible compression for the thermally conductive pads makes it difficult to accommodate these pads in an electronic assembly.